Electricity is non-existent in waterways. As marine docks in the water become safety hazards at nighttime if they are not seen by a boater, it is important to provide some mechanism to alert or inform a boater at night to their existence. The lighting of the deck or dock itself can be costly and also creates new problems based on the corrosive nature of water and electricity. Furthermore, logistical distance often prevents electrical power from being installed on many docks, decks and pilings. Accordingly, the below disclosed piling cap provides a novel device for illuminating one or more pilings, without the need for electrical power to be present at the dock, deck, pier, etc. and in turn may also illuminate the docks, decks, piers, etc. they are associated with during nighttime hours.